Multiple Sclerosis (MS) is an autoimmune disease of the CNS of unknown etiology that affects ˜400 000 Americans. In MS, myelin reactive T cells enter into the brain and spinal cord and mediate destruction of the myelin sheath surrounding neurons resulting in progressive motor dysfunction and eventual paralysis. Current treatment strategies include switching the pro-inflammatory Th1 T cell phenotype to an anti-inflammatory Th2 response, preventing encephalitogenic T cells from extravasating into the brain, inducing T cell tolerance, anergy or apoptosis, and repairing or replacing damaged CNS cells, such as neurons and oligodendrocytes.
The course of disease is highly varied and unpredictable. In most patients, especially when MS begins with optic neuritis, remissions can last months to >10 yr. However, some patients have frequent attacks and are rapidly incapacitated, although life span is shortened only in very severe cases.
Goals for therapy include shortening acute exacerbations, decreasing frequency of exacerbations, and relieving symptoms; maintaining the patient's ability to walk is particularly important. Acute exacerbations may be treated with brief courses of corticosteroids. However, although they may shorten acute attacks and perhaps slow progression, corticosteroids have not been shown to affect long-term outcome.
Immunomodulatory therapy decreases frequency of acute exacerbations and delays eventual disability. Immunomodulatory drugs include interferons (IFNs), such as IFN-β1b and IFN-β1a. Glatiramer acetate may also be used. Other potential therapies include the immunosuppressant methotrexate and Natalizumab, an anti-α4 integrin antibody that inhibits passage of leukocytes across the blood-brain barrier. Immunosuppressants such as mycophenolate and cyclophosphamide have been used for more severe, progressive MS but are controversial.
In addition to suppressing the pathological immune response it is important to protect CNS cells from further damage and to induce repair of injured cells since some cells such as neurons have few progenitors in the adult mammalian brain and are thus limiting.
Compositions and methods for treating MS are of great clinical interest. The present invention addresses this issue.